José Pedro Segundo

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This paper studies the influence exerted by the presynaptic spike train on the postsynaptic one. It applies to synaptic exploration a novel method for characterization of point-process systems (Brillinger, 1974, 1975a), and draws from it physiologically meaningful conclusions. The departure point was a large data set of action potential trains from an(More)
An elementary model of neuronal activity involves temporal and spatial summation of postsynaptic currents that are elicited by presynaptic spikes and that, in turn, elicit postsynaptic potentials at a trigger zone; when the potential at the trigger zone exceeds a “threshold” level, a postsynaptic spike is generated. This paper describes three methods of(More)
This communication describes the new information that may be obtained by applying nonlinear analytical techniques to neurobiological time-series. Specifically, we consider the sequence of interspike intervals Ti (the "timing") of trains recorded from synaptically inhibited crayfish pacemaker neurons. As reported earlier, different postsynaptic spike train(More)
Mit Hilfe eines Digitalrechners wurden die Eingangs-und Ausgangsbeziehungen auf synaptischer Ebene untersucht und dargestellt. Diese Untersuchung erstreckt sich auf erregende Synapsen und analysiert die Veränderungen postsynaptischer Aktionspotentiale, die auftreten, 1. wenn die Anzahl der präsynaptischen axonischen Endigungen ansteigt, während andererseits(More)
The presynaptic fiber at an inhibitory synapse on a pacemaker neuron was forced to generate transients, defined here as spike trains with a trend, unceasingly accelerating or slowing. Experiments were on isolated crayfish stretch receptor organs. Spike train analyses used tools and notions from conventional point processes and from non-linear dynamics. Pre-(More)
The pooled spike trains of correlated presynaptic terminals acting synchronously upon a single neuron are realizations of cluster point processes: the notions of spikes synchronizing in bursts and of points bunching in clusters are conceptually identical. The primary processes constituent specifies the timing of the cluster series; subsidiary processes and(More)
Our aim was to examine the relation, or "synaptic coding", between spike trains across a synapse with inhibitory postsynaptic potentials when the presynaptic rate is modulated periodically and the postsynaptic cell is a pacemaker. Experiments were on the synapse in crayfish stretch receptor organs. Spike trains were considered point processes along time;(More)
A simple mathematical model of living pacemaker neurons is proposed. The model has a unit circle limit cycle and radial isochrons, and the state point moves slowly in one region and fast in the remaining region; regions can correspond to the subthreshold activity and to the action potentials of pacemaker neurons, respectively. The global bifurcation(More)
1. The spike discharges of single first order afferents from the utricle were recorded in the isolated head of the guitarfish and tested for responses to maintained spatial orientation, to transitions and to a small positional jitter representing natural perturbations. Sensitivity to maintained orientation is referred to as “tonic,” and to transitions and(More)
It is known (e.g., Perkel et al., 1964) that when a pacemaker neuron elicits IPSP's in another, there are domains called “paradoxical segments” where in the steady-state i) faster inhibitory discharges determine faster inhibited ones, and ii) pre- and postsynaptic spikes are “locked” in an invariant forward-and-backward positioning in time, spikes(More)